Silicon substrates are used in the fabrication of semiconductors and solar cells. During fabrication, substrates are subjected to various manufacturing processes involving numerous machines and process stations. Thus, the substrates need to be transported from one machine/station to another machine/station one or more times.
The transport of the substrates between machines/stations is often performed by robots having support structures, commonly referred to as “end effectors,” for supporting and manipulating the substrates in a desired manner. An end effector may be a hand-like or claw-like structure defined by a base with a plurality of fingers or tines extending therefrom. The fingers may be adapted to support a substrate in a horizontal orientation. During operation, the end effector may be moved linearly (e.g., forward and backward) as well as rotationally, all in the same plane (e.g., x-y axis). The end effector may also be moved in a third direction along a z-axis to provide a full range of motion.
When an end effector is moved, the fingers of the end effector may be subjected to significant acceleration forces, causing the fingers to flex and subsequently vibrate according to natural frequencies of the fingers. Such vibration can result in unintended shifting or “walking” of substrates supported by the fingers. This may be highly detrimental to subsequent process steps, especially if a precise arrangement or orientation of the substrates is desired. Vibration can be mitigated by reducing the acceleration of an end effector during movement thereof. Such reductions result in decreased throughput of substrates through a process tool, and are thus generally undesirable.
With respect to these and other considerations the current improvements may be useful.